I have a Gator case I got from a local store, but it fits well. Check out where you can order Gator cases from. It is actually a dread case, but the OM fits in there nicely. I little room at the bottom, but the lower bout and the heel of the neck hold everything in place perfectly.

Musician's Friend has a line of cases with their name on them. Not too fancy, but decently made and plenty of protection for around the house. I have one of their dreadnaught cases but they also have a Classical case that may fit an OM. The dimensions are listed on their web site at www.musiciansfriend.com

I have several of the Musicians Friend classical cases that fit the OM fine. For the price, you can't beat their cases. They aren't Ameritage cases but they aren't a couple hundered bucks either. Here is a link to the case. I have 4 of the classical and two dreadnought cases and couldn't be happier with them for the cost. And if you watch, they do free shipping all the time on orders $49.99 and up. Add a pack of strings to the order and you get over the limit for free shipping.